1. Field of the Present Invention
The present invention generally relates to the field of data processing systems and more particularly to a system and method for reducing energy consumption in a multi-processor system by selectively powering down one or more processors during periods of reduced activity.
2. History of Related Art
In the field of data processing systems, multi-processor systems are well known. For purpose of this disclosure, a multi-processor system refers generally to any system in which two or more microprocessors share access to common system memory typically comprised of dynamic random access memory (DRAM) or other suitable volatile memory element. Multi-processor systems offer the potential for improved performance by allowing more than one processor to execute portions of a data processing problem simultaneously. In one common example of a multi-processor system, a single system memory is shared by a set of processors connected to the memory via a common system bus. This embodiment is frequently referred to as a symmetric multiprocessor (SMP) system because each processor has substantially equivalent access to the system memory.
SMP systems and other multi-processor systems are frequently used in high performance applications such as enterprise servers and the like. Such systems characteristically experience periods of high activity, when all of the system's processors are operating at or near their theoretical potential, and periods of low activity, when the cumulative processing power greatly exceeds the demand. General purpose microprocessors, especially in high performance systems, are expensive to operate in part because of the large amount of electric current (i.e., power) they draw. As processors have increased in performance capability and complexity, the transistor count in these processors has increased accordingly while the minimum dimension of each transistor has decreased. A larger number of smaller transistors generally results in increased power consumption current due to sub-micron effects that are familiar to those in the field of semiconductor physics.
Recently, the amount of power consumed by server devices has become of paramount significance as large clusters of server devices are connected together in a single room. If the power consumption of the server devices is not controlled, the amount of energy consumed and the corresponding amount of heat dissipated in such rooms may negatively impact the performance or even functionality of a server or group of servers in addition to driving up the overall cost of operation. Accordingly, it would be highly desirable to implement a system and method in which the energy consumed by a multiprocessor system is reduced or minimized by selectively powering off processors during periods of reduced activity and enabling these processors during peak loading periods